1. Technical Field
The present disclosure relates to razor blades for razor cartridges in general and, more particularly, to a method of manufacturing a razor blade.
2. Background
Many modern safety razors include a disposable razor cartridge adapted to be selectively connected to a reusable handle by connecting structure therebetween. The cartridge includes a housing having at least one razor blade with a cutting edge disposed therein. Other modern safety razors include a razor cartridge permanently connected to the handle that can be disposed of as a single unit.
In commonly assigned U.S. patent application Ser. No. 11/150,744, published as US 2006/0277759, now U.S. Pat. No. 7,681,314, the desirability of providing a razor blade assembly including an inter-blade guard joined to a razor blade is disclosed. The provision of an inter-blade guard permits adjacent cutting edges to be spaced sufficiently far apart in their razor cartridge to allow adequate rinsing of debris from the space between adjacent blades and any respective support structure while the inter-blade guard provides a skin engaging/skin supporting surface between adjacent cutting edges to control skin bulge and provide improved shaving comfort and reduction of nicks and cuts. The inter-blade guard is mounted on the razor blade in a position generally visible to a user during normal use and handling of the safety razor.
A razor cartridge including a razor blade having a bent portion can have certain advantages and there have been many proposals to provide a razor cartridge with such a razor blade. However, such razor cartridges have not been successfully commercialized or at least not manufactured on a scale that is significant in a mass market such as that of razor cartridges. Many manufacturers emulate a bent razor blade by mounting a generally planar razor blade on a bent support made from a material both thicker and softer than a typical hardened razor blade. U.S. Pat. No. 4,586,255 to Jacobson discloses a typical construction of a blade mounted on a support. The support is mounted on the opposed side of the razor blade to the blade guard of the aforementioned U.S. Pat. No. 7,681,314 the razor blade and is at least partially hidden from view by a user during normal use and handling of the safety razor.
Modern safety razors are normally used and can be stored by a user in a more or less wet or humid environment. In normal use, the razor blades of a razor cartridge are brought into contact with mildly corrosive substances, such as the constituents of sweat, soap, and shaving aids such as shaving foam or gel. Also the nature and composition of tap water (which is generally used for shaving) can vary from city to city. In view of these ambient conditions, martensitic stainless steels have become widely used as a corrosion-resisting material for making razor blades having a high level of cutting quality.
The inter-blade guard on the other hand is preferably manufactured from a fully annealed low-carbon stainless steel such as grade AISI 301/DIN 1.4310. This material is chosen for several reasons including ease of forming its desired profile, such as those disclosed in the aforementioned U.S. Pat. No. 7,681,314. For convenience of assembly, the inter-blade guard can be joined by welding, e.g. laser spot welding, to its respective razor blade.
Small compositional differences can thus exist between the razor blade and its inter-blade guard assembled thereto. In use, moisture and other constituents can be trapped and retained between the razor blade and its inter-blade guard. This can act as an electrolyte and thus the razor blade, inter-blade guard and moisture therebetween can comprise an electrochemical cell that can result in localized electrochemical corrosion of the razor blade. As the inter-blade guard is mounted on the razor blade in a position visible to a user any such corrosion can also be visible to a user and can be at least considered unsightly and may cause real or perceived premature failure of the razor blade and thus razor cartridge having such a razor blade assembly. Moreover, many modern safety razor cartridges can have an extended useful life compared to earlier razor cartridges. Improved coatings on cutting edges (e.g. hard carbon) can increase the useful life of the cutting edge and improvements in the composition or construction of so-called lubricating strips can extend the life of the lubricating strip. A modern safety razor cartridge having an extended life has more opportunity to suffer corrosion during its life than an earlier razor cartridge.